510 



THE AMERICAN NATURALIST 



[Vol. XL 



leaf represented the normal leaves of ancient Corriptonia plants. 

 The former view seems to me doubtful, not onlv because of the 

 perishable nature of seedhng leaves in general, but because it is 

 unusual for them to become detached and iossihzcd. 1 luit rhev 

 are sometimes found as fossils is proven bv the leave- tioiii the 

 Swiss Tertiarv which Heer calls Myrwa Uttilnlxi /■/. / ,rt. 1 1 dr., 

 vol. 3, p. 176, pi. 150, figs. 12-10. 1S5()). Fiu ilicnnoic no other 

 species of Comptonia has been toiind in the ivantan chivs or 

 Patoot schists from which thcv could have bct ii derived. \\e are 

 quite justified in concluding that these leaves aic the normal leaves 

 of the earliest known Comptoinas and that the modern seedhng 

 leaves are trulv atavistic, hroni the abundance of the genus 

 Myrica with nine species m the Ivaritan. we nuiv assume that the 

 Comptonia stock became separated tioin Mvrica some time dur- 

 ing the lower Cretaceous. prol)al)lv towaid its close. While the 

 leaf A^hich Heer calk Rhus IS probabh tioni . .liJ.iK hi Ji, i l.oii- 

 zon than the Raritan leaf, its smaller si/t md its o((urrence near 

 what was probal)lv the oritjmal center ol radiation ot the genus 

 Comptonia, stainj) it as the real starting point for anv scheme ol 



close rtlatioil it not u tual idt ntitx Ixtuun tht m lomisof the 

 New \\orld ami Cnnptonni (u,ti<i>m Xilss. of l-lurope. 



There are four si)ecies ot Mvnca m the Atane fh^ra and two in 



l)etween Mvrica and ( \>inptonia at this time, althoimb I am stn.nolv 

 mdmtd to thmk that Miincu praco.r is a Qnercus to which genus 

 all ot the early ( omptomas show a passing resemblance, partic- 

 ularlv the Raritan leaf. 



Comptoma oemngensis Al. Br 



